ELECTRICAL-CONDUCTIVITY IN HETEROGENEOUS ORGANIC POLYMERIC SYSTEMS

Eight main groups of organic heterogeneous electrically conducting pol ymers are discussed: conducting colloid composites, blends of processa ble conducting and inert polymers, conducting polymers filled matrices , composites obtained by polymerization of conjugated polymers within insulating matrix, conducting polymer salts with polymeric counterions , mixtures of insulating polymer matrices and of conducting crystals ( ''organic metals''), reticulate doped polymers consisting of crystalli ne network of ''organic metals'' interpenetrating polymer matrix, inor ganic/organic hybrid materials. In heterogeneous systems different mec hanisms can contribute to the charge carrier transport: high-mobility motion in ordered regions, hopping among localized states in disordere d regions; tunneling between highly conducting islands - all controlle d by the percolation process. Theoretical models are discussed from th e point of view of their experimental implications: temperature, field and pressure dependences of d.c. conductivity, frequency dependences of a.c. conductivity, thermopower. In spite of structural diversity of heterogeneous organic polymeric systems in most cases their electrica l behavior is described by models based on variable-range-hopping or b y tunneling mechanisms.